/*
 *  Copyright (c) 2017 Uber Technologies, Inc. (hoodie-dev-group@uber.com)
 *
 *  Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *           http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 *
 */

package com.uber.hoodie.utilities.schema;

import com.uber.hoodie.DataSourceUtils;
import com.uber.hoodie.common.util.FSUtils;
import com.uber.hoodie.common.util.TypedProperties;
import com.uber.hoodie.exception.HoodieIOException;
import java.io.IOException;
import java.util.Arrays;
import org.apache.avro.Schema;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.spark.api.java.JavaSparkContext;

/**
 * A simple schema provider, that reads off files on DFS
 */
public class FilebasedSchemaProvider extends SchemaProvider {

  /**
   * Configs supported
   */
  public static class Config {
    private static final String SOURCE_SCHEMA_FILE_PROP = "hoodie.deltastreamer.schemaprovider"
        + ".source.schema.file";
    private static final String TARGET_SCHEMA_FILE_PROP = "hoodie.deltastreamer.schemaprovider"
        + ".target.schema.file";
  }

  private final FileSystem fs;

  private final Schema sourceSchema;

  private Schema targetSchema;

  public FilebasedSchemaProvider(TypedProperties props, JavaSparkContext jssc) {
    super(props, jssc);
    DataSourceUtils.checkRequiredProperties(props, Arrays.asList(Config.SOURCE_SCHEMA_FILE_PROP));
    this.fs = FSUtils.getFs(props.getString(Config.SOURCE_SCHEMA_FILE_PROP), jssc.hadoopConfiguration());
    try {
      this.sourceSchema = new Schema.Parser().parse(
          fs.open(new Path(props.getString(Config.SOURCE_SCHEMA_FILE_PROP))));
      if (props.containsKey(Config.TARGET_SCHEMA_FILE_PROP)) {
        this.targetSchema = new Schema.Parser().parse(
            fs.open(new Path(props.getString(Config.TARGET_SCHEMA_FILE_PROP))));
      }
    } catch (IOException ioe) {
      throw new HoodieIOException("Error reading schema", ioe);
    }
  }

  @Override
  public Schema getSourceSchema() {
    return sourceSchema;
  }

  @Override
  public Schema getTargetSchema() {
    if (targetSchema != null) {
      return targetSchema;
    } else {
      return super.getTargetSchema();
    }
  }
}
